As integrated circuits have seen increased use in recent years, the integration of multiple functions onto a single chip has also increased. Although purely digital circuits require a common technology with respect to transistors, i.e., all CMOS transistors, analog circuitry requires a different technology for such devices as bipolar devices. Each technology facilitates itself to a common processing technology for common devices when only that technology is involved and required. However, whenever audio systems are combined with digital systems, analog technology must be merged with digital technology. This can create problems due to the fact that analog circuitry is sometimes incompatible with the digital clocking signals, especially with respect to analog-to-digital converters. Very high resolution analog-to-digital converters or digital-to-analog converters can be affected by noise created in the digital circuitry. When merging the two technologies together, this is referred to as “mixed-signal” technology.
In current mixed-signal technology, it is desirable to combine the functionality of a microprocessor or microcontroller with an interface to the analog domain through an analog-to-digital converter or a digital-to-analog converter. Further, for many applications, there is a desire for configurability to allow various functions to be emulated or realized with the circuit. Some instrumentation applications require such. The application could be achieved with multiple integrated circuits configured in many different ways, but the desire is for a single chip solution.